ADR: Attention Diversification Regularization for Mitigating Overfitting in Multiple Instance Learning Based Whole Slide Image Classification

Multiple Instance Learning (MIL) has demonstrated effectiveness in analyzing whole slide images (WSIs), yet it often encounters overfitting challenges in real-world applications. This paper reveals the correlation between MIL's performance and the entropy of attention values. Based on this observation, we propose Attention Diversity Regularization (ADR), a simple but effective technique aimed at promoting high entropy in attention values. Specifically, ADR introduces a negative Shannon entropy loss for attention values into the regular MIL framework. Compared to existing methods aimed at alleviating overfitting, which often necessitate additional modules or processing steps, our ADR approach requires no such extras, demonstrating simplicity and efficiency. We evaluate our ADR on three WSI classification tasks. ADR achieves superior performance over the state-of-the-art on most of them. We also show that ADR can enhance heatmaps, aligning them better with pathologists' diagnostic criteria. The source code is available at \url{https://github.com/dazhangyu123/ADR}.